diff --git a/libraries/DataFlash/DataFlash_Backend.cpp b/libraries/DataFlash/DataFlash_Backend.cpp
index edcaa6d2fe3..40f700566f6 100644
--- a/libraries/DataFlash/DataFlash_Backend.cpp
+++ b/libraries/DataFlash/DataFlash_Backend.cpp
@@ -50,6 +50,10 @@ void DataFlash_Backend::periodic_tasks()
     periodic_fullrate(now);
 }
 
+void DataFlash_Backend::start_new_log_reset_variables()
+{
+    _startup_messagewriter->reset();
+}
 
 void DataFlash_Backend::internal_error() {
     _internal_errors++;
diff --git a/libraries/DataFlash/DataFlash_Backend.h b/libraries/DataFlash/DataFlash_Backend.h
index b1722821904..916bafedd72 100644
--- a/libraries/DataFlash/DataFlash_Backend.h
+++ b/libraries/DataFlash/DataFlash_Backend.h
@@ -132,6 +132,9 @@ protected:
     uint32_t _internal_errors;
     uint32_t _dropped;
 
+    // must be called when a new log is being started:
+    virtual void start_new_log_reset_variables();
+
 private:
 
     uint32_t _last_periodic_1Hz;
diff --git a/libraries/DataFlash/DataFlash_File.cpp b/libraries/DataFlash/DataFlash_File.cpp
index 0aef56cea84..42c803ca749 100644
--- a/libraries/DataFlash/DataFlash_File.cpp
+++ b/libraries/DataFlash/DataFlash_File.cpp
@@ -803,7 +803,7 @@ uint16_t DataFlash_File::start_new_log(void)
 {
     stop_logging();
 
-    _startup_messagewriter->reset();
+    start_new_log_reset_variables();
 
     if (_open_error) {
         // we have previously failed to open a file - don't try again
diff --git a/libraries/DataFlash/DataFlash_MAVLink.cpp b/libraries/DataFlash/DataFlash_MAVLink.cpp
index b9d1d6397b1..d95999e5145 100644
--- a/libraries/DataFlash/DataFlash_MAVLink.cpp
+++ b/libraries/DataFlash/DataFlash_MAVLink.cpp
@@ -231,7 +231,7 @@ void DataFlash_MAVLink::handle_ack(mavlink_channel_t chan,
             _target_component_id = msg->compid;
             _chan = chan;
             _next_seq_num = 0;
-            _startup_messagewriter->reset();
+            start_new_log_reset_variables();
             _last_response_time = AP_HAL::millis();
             Debug("Target: (%u/%u)", _target_system_id, _target_component_id);
         }